Washing and deliming composition for limed hides



Patented May 4, 1943 WASHING AND nELiMiNG COMPOSITION ron LIMED HIDES INo Drawing. Application July 13, 1940,

- Serial No. 345,414

4 Claims.

This invention relates to washing and deliming compositions for limedhides, furs and the like.

It is known that the pH value of the adhering liquids of hides, theamount of swelling, and the amount of hydrolysis of the collagenmaterially afiect treatment operations involving hides and hairs and toa great extent the quality of the resulting leather.

It is almost a universal practice to remove hairs from various skins bysoaking them in a lime bath until the hairs are sufliciently loosened tobe easily removed either by hand or by unhairing' machinery. When thehides have reached a state where the hairs are sufliciently loosened,they are removed and unhaired. Then it is necessary to delime the hidesso as to bring them into a proper state of alkalinity and to preventundue swelling and disintegration of the leather-forming portions of thehides. Numerous agents have been suggested for use in deliming baths butmost of these agents have proven unsatisfactory due to the fact thatthey cause excessive swelling of the hides, are ineflicient in use orresult in an insuflicient removal of lime.

It is an object of thepresent invention to provide improved deliming andalkalinity controlling compositions for use in deliming baths.

7 The compositions of the present invention contain primarily first runfatty acids of 4. to 6 carbon atoms derived from distilling theoxidation products of parafiin hydrocarbons in combination with a. smallpercentage of the ammonium salt of sulfonated oleyl alcohol, and an evensmaller percentage of triethanol amine. constituent may be designated asmid-fraction fatty acids and contain more than 3 carbon atoms and lessthan 8 carbon atoms in the fatty acid radicals. Other water-solublesalts of the imsaturated higher molecular fatty alcohol sulfonates maybe used in the compositions of the invention with somewhat lesssatisfactory results.

The fatty acid acids. Agitation is continued until a stable homogeneousmass is provided. This product is provided for the trade in an anhydrouscondition and is very active when mixed with aqueous washing baths fordeliming.

The compositions of the present invention do not contain any mineralacids or salts to react with the hides to produce swelling. Hence theyproduce a very mild effect upon the hides being treated and do notresult in a deleterious swelling. On the other hand, these mildly activeorganic compounds form readily soluble-lime salts with the lime presentin the unhaired hides. These salts are not adsorbed or absorbed in thestruc-. ture of the hide and are easily washed out in the deliming bathor in subsequent rinsing baths.

It has been found that much smaller percentages of the compositions ofthe present invention are efiective for addition to the treatment bathsin the deliming operations than has been necessary with prior delimingcompositions. In fact, percentages which are one-third of thoseheretofore used with known deliming and washing agents have proven to beeffective. Naturally the amount of deliming agent will depend somewhatupon the amount of lime present in the hide structure, the type of hidebeing treated and the kind of leather to be produced. However, de-

, liming baths incorporating less than 1% of the A typical compositionof the nature of the ones The fatty acids used in the above example havean acid number of 516, a saponification number of 530, an iodine numberof 7, a hydrogen number of 0 and an average molecular weight of 106.

The compositions are usually prepared by introducing the sulfonatedalcohol and the triethanol amine into a vessel provided with an agitatorwhich contains the lower molecular fatty deliming compositions of thepresent invention have proven to be amply satisfactory. In fact, lessthan .5% of these compositions are usually suflicient. In accordancewith the preferred practice the deliming bath is gradually brought tothe proper strength by small additions of the deliming agent. This isespecially true -when treating sensitive hides. The deliming bathsusually contain from 200% to 600% water based on the weight of theunhaired hides. The preferred temperature of the bath ranges from 28 toC. a

The following examples serve to indicate typical deliming treatmentbaths for the production of special leathers from various types ofhides.

Percentage of deliming Kind of Type of Length of composition hideleather treatment CBIL B 1 (s rifle ox do .t. 1 do 'Chevnettes" K Do.do.. Case Do.

The compositions of the present invention are so effective in theirdeliming function that substantially all the lime can be removed fromthe hides. Bating agents, therefore, frequently are unnecessary. If theuse or hating agents is felt 2,318,454 UNITED STATES PATENT "OFFICEdesirable, they can be a ded to the deliming baths'per set without thenecessity of providing separate baths. Hides treated with the delimingagents of the present invention are clear and clean and have a delicategrain. The resulting leathers have good fullness, a close solid grain,

sulfonated higher molecular unsaturated pri-' mary alcohol andtriethanol amine.

2. A deliming composition consisting essentially of 95 parts or fattyacids of 4 to 6 carbon atoms, 4 parts of the ammonium salt of commercialoleyl alcohol sulfonate and 1 part of triethanol amine.

3. An aqueous treating bath for deliming hides containing less than .5%of a deliming agent containing a mid-fraction fatty acid of 4 to 6carbon atoms, an ammonium salt of sulionated oleyl alcohol andtriethanol amine.

4. A process for deliming hides which comprises subjecting a hide to thedeliming action of an aqueous treating bath containing as a deliming andcleaning agent a composition consisting of a fatty acid of 4 to 6 carbonatoms, the ammonium salt of suifonated oleyl alcohol and triethanol.amine, said treatment taking place at a temperature of 28 to 35 C.

' HEINRICH BERTSCH.

FRIEDRICH SCHMI'I'I.

